Syed LCS G4ModelPaper

LCS in G4

describe below the performance of the Compton scattering models in G4 and motivate reference frame boost approach.

Abstract

Tunable and quasi-monochromatic laser Compton scattered (LCS) X-rays are produced as a result of the interaction between accelerated electrons and a laser beam. The energy tunability of LCS X-rays is dependent on the incoming electron and laser beam energies.

quantify SNR improvement

The quasi-monochromatic nature of LCS X-rays improve the performance of radiography applications due to the higher signal-to-noise ratio compared to conventional X-ray tubes.

quantify significantly

Significantly lower X-ray doses per image both to the object/patient and workers are possible.

Previously, two 20.94 keV and 98.4 keV LCS peaks, having a FWHM = ???, were produced at the Idaho Accelerator Center (IAC) in two separate experiments using electron beam energies of ~34 MeV and ~37 MeV respectively that intersected a 4 GigaWatt peak power Nd:YAG laser operating at wavelengths of 1064 nm and 266 nm. The electron linear accelerator (linac) was operating at 60 Hz with an electron beam pulse length of 50 ps and a peak current of 7 Amps. A simulation has been performed using a Geant4 Monte Carlo simulation toolkit to further understand features of the experimental yield, such as the influence of the energy distribution of the incoming electron beam. A comparison between simulated and experimental LCS X-rays of ~20 keV and ~98 keV as well as radiographic images of fish and lead samples will be shown.

Acknowledgements. The authors gratefully acknowledge the support of this project from the Department of Defense (DOD) under contract, DOD#FA8650-04-2-6541.

Introduction

Theory

The differential cross section describing the Compton scattering of a photon by an electron at rest is given by the Klein-Nishina formula ~\cite{KleinNishina1929} as:

[math]\frac{d \sigma}{d \Omega} = \frac{r_e^2}{2} \frac{1 + \cos^2(\theta) + \frac{\xi^2 \left [ 1+ \cos(\theta) \right ]^2}{1 + \xi \left( 1+ \cos(\theta) \right)}}{\left[ 1+ \xi (1-\cos(\theta) ) \right ]^2}[/math]

where [math]r_e[/math] is the bohr radius, [math]\theta[/math] is the electron photon scattering angle and

[math]\xi = \frac{h \nu}{m_e c^2} = \frac{E_{\gamma}}{E_0^{e^-}} [/math]

References

\cite{KleinNishina1929} Oskar Klein & Yoshio Nashina, Z. Phys., vol 52 (1929), pg 853 )

2.) GEANT4

3.) Reference for GEANT4 Compton scattering Model

Stepanek NIMA 412 1998pg174.pdf say

BNL-47503

BNL-

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